It speaks to Parker's immense potential that despite having his 2009 season cut short and missing 2010 completely, he is still ranked 29th on MLB.com's Top 50 Prospects list.

The 2007 first-round pick seemed to be on the fast track to the Majors before he experienced discomfort in his elbow during a start for Double-A Mobile on July 30, 2009. After trying to strengthen the area for a few months, he finally had surgery in early October.

From then on, it was all about rehab for Parker, who spent a lot of that time at the club's rehab facility in Tucson, Ariz., far away from his Indiana home and separated from his teammates.

Known for his competitive nature on the field, Parker threw himself completely into the rehab process and drew praise for his approach from the organization's medical staff.

"It was something I didn't want to have any doubt about whether or not I had put in the full effort," Parker said. "I gave it everything I had. I learned a lot of other things around the game during that time about having a game plan, hitter recognition and attention to detail. It helped me develop a little more of a mental approach and become more in tune with my body, my arm and what I need to do to stay healthy."

The effort paid off as Parker was able to pitch in some instructional league games last fall, which whet his appetite for 2011.

Following his instructional league stint, Parker took some time off from throwing before coming to Phoenix on Monday. He played catch Tuesday and is scheduled to throw his first bullpen session Friday. That will likely be around 20-25 pitches, mainly fastballs and changeups.

New D-backs general manager Kevin Towers got his first look at Parker last October and liked what he saw, saying he reminds him of Jake Peavy, who pitched for Towers in San Diego.

Towers has said that the plan would be for Parker to begin the 2011 season at Mobile, where the weather will likely be better than Triple-A Reno. At the same time, Towers did not completely rule out Parker's chances of making the team out of Spring Training.

Whether he makes the team this spring or not, there's a good chance Parker will see some big league action this year, and make no mistake, that is exciting to him, but it's not his main focus right now.

"It's in the back of my mind, sure," Parker said. "But I'm more focused on just getting ready for the season. I'm definitely looking forward to showing people I'm healthy. After surgery, everyone is kind of skeptical about how you'll bounce back and respond. I'm definitely going to be full go and no limitations once Spring Training and the season get going."

The D-backs, though, figure to be cautious with his innings total this year given his age and the fact that he did not pitch last summer. He threw just 117 2/3 innings in 2008 and 97 1/3 in 2009.